Veusz is a scientific plotting package, designed to create publication-ready Postscript, PDF, or SVG output. It features an easy to use graphical interface as well as a command line interface and can be scripted or embedded in Python scripts. Graphs are constructed in a modular fashion from separate components. Datasets can be interactively modified or created from within the program.
SynchroDir is a backup and synchronization utility. Each backup is the subject of a recordable "backup project". This feature allows you to save projects corresponding to different computers, servers, external hard drives, USB keys, etc. You can also backup data of computer Y to computer Z from a controlling computer X. Each backup project includes an unlimited number of "jobs". At the end of the backup process, a log file is available. Each job has a source and a destination, each corresponding to a volume or a directory. The volume or directory must be "mounted", either locally or over the network.
Trojita is a Qt IMAP email client. It is a pure Qt4 application with no additional dependencies. It has a robust IMAP core implemented using Qt's Model-View framework. Standards compliance is a design goal. It has support for bandwidth-saving mode aimed at mobile users with expensive connections. In addition to the usual SSL/TLS connections, the server can be accessed via SSH. It has on-demand body part loading, offline IMAP support, and safe dealing with HTML mail (actually more robust than Thunderbird's).
DireKtion is a satellite navigation project based on data from OpenStreetMap.org. It aims to provide a free (not just as in beer) satellite navigation solution for any vehicle/person that can carry a Linux device. It is able to calculate a route between any two points on a map, and displays directions for traveling between them.